Having hard time making sense of Stack Trace

Question

I am having hard time re-producing the scenario or reading the below error I got on my logs today.. normally the stack trace would point to the file and line number and such but as you can see below it only says nullreference exception without giving me the specific location.. I would appreciate if you can help me read into this and find out what exaclty is happening..

System.Web.HttpException (0x80004005): Error executing child request for handler 'System.Web.Mvc.HttpHandlerUtil+ServerExecuteHttpHandlerWrapper'. ---> System.Web.HttpUnhandledException (0x80004005): Exception of type 'System.Web.HttpUnhandledException' was thrown. ---> System.NullReferenceException: Object reference not set to an instance of an object.
  at ASP.views_reservation_checkout_aspx.__RenderContent2(HtmlTextWriter __w, Control parameterContainer)
  at System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children)
  at ASP.content_kismetvacation_views_shared_site_master.__RenderBodyContent(HtmlTextWriter __w, Control parameterContainer)
  at System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children)
  at ASP.content_kismetvacation_views_shared_site_master.__Render__control1(HtmlTextWriter __w, Control parameterContainer)
  at System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children)
  at System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children)
  at System.Web.Mvc.ViewPage.Render(HtmlTextWriter writer)
  at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
  at System.Web.UI.Page.HandleError(Exception e)
  at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
  at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
  at System.Web.UI.Page.ProcessRequest()
  at System.Web.UI.Page.ProcessRequest(HttpContext context)
  at System.Web.Mvc.ViewPage.ProcessRequest(HttpContext context)
  at System.Web.Mvc.HttpHandlerUtil.ServerExecuteHttpHandlerWrapper.<>c__DisplayClass4.<Wrap>b__3()
  at System.Web.Mvc.HttpHandlerUtil.ServerExecuteHttpHandlerWrapper.Wrap[TResult](Func`1 func)
  at System.Web.HttpServerUtility.ExecuteInternal(IHttpHandler handler, TextWriter writer, Boolean preserveForm, Boolean setPreviousPage, VirtualPath path, VirtualPath filePath, String physPath, Exception error, String queryStringOverride)
  at System.Web.HttpServerUtility.ExecuteInternal(IHttpHandler handler, TextWriter writer, Boolean preserveForm, Boolean setPreviousPage, VirtualPath path, VirtualPath filePath, String physPath, Exception error, String queryStringOverride)
  at System.Web.HttpServerUtility.Execute(IHttpHandler handler, TextWriter writer, Boolean preserveForm, Boolean setPreviousPage)
  at System.Web.HttpServerUtilityWrapper.Execute(IHttpHandler handler, TextWriter writer, Boolean preserveForm)
  at System.Web.Mvc.ViewPage.RenderView(ViewContext viewContext)
  at System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context)
  at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass14.<InvokeActionResultWithFilters>b__11()
  at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation)
  at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult)
  at System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName)
  at System.Web.Mvc.Controller.ExecuteCore()
  at System.Web.Mvc.MvcHandler.<>c__DisplayClass8.<BeginProcessRequest>b__4()
  at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass1.<MakeVoidDelegate>b__0()
  at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
  at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
System.Web.HttpUnhandledException (0x80004005): Exception of type 'System.Web.HttpUnhandledException' was thrown. ---> System.NullReferenceException: Object reference not set to an instance of an object.
  at ASP.views_reservation_checkout_aspx.__RenderContent2(HtmlTextWriter __w, Control parameterContainer)
  at System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children)
  at ASP.content_kismetvacation_views_shared_site_master.__RenderBodyContent(HtmlTextWriter __w, Control parameterContainer)
  at System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children)
  at ASP.content_kismetvacation_views_shared_site_master.__Render__control1(HtmlTextWriter __w, Control parameterContainer)
  at System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children)
  at System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children)
  at System.Web.Mvc.ViewPage.Render(HtmlTextWriter writer)
  at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
  at System.Web.UI.Page.HandleError(Exception e)
  at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
  at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
  at System.Web.UI.Page.ProcessRequest()
  at System.Web.UI.Page.ProcessRequest(HttpContext context)
  at System.Web.Mvc.ViewPage.ProcessRequest(HttpContext context)
  at System.Web.Mvc.HttpHandlerUtil.ServerExecuteHttpHandlerWrapper.<>c__DisplayClass4.<Wrap>b__3()
  at System.Web.Mvc.HttpHandlerUtil.ServerExecuteHttpHandlerWrapper.Wrap[TResult](Func`1 func)
  at System.Web.HttpServerUtility.ExecuteInternal(IHttpHandler handler, TextWriter writer, Boolean preserveForm, Boolean setPreviousPage, VirtualPath path, VirtualPath filePath, String physPath, Exception error, String queryStringOverride)

Answer 1

The top line of the stack trace is from the deepest point (where the error occurred) and the following lines as it bubbles back up the stack.

I removed the System.* entries (where it dips into the .NET Framework) and what's left are your pages and classes, for the most part. It makes it a bit more readable, maybe more manageable ...

System.Web.HttpException (0x80004005): Error executing child request for handler 'System.Web.Mvc.HttpHandlerUtil+ServerExecuteHttpHandlerWrapper'. ---> System.Web.HttpUnhandledException (0x80004005): Exception of type 'System.Web.HttpUnhandledException' was thrown. ---> System.NullReferenceException: Object reference not set to an instance of an object.
  at ASP.views_reservation_checkout_aspx.__RenderContent2(HtmlTextWriter __w, Control parameterContainer)
  at ASP.content_kismetvacation_views_shared_site_master.__RenderBodyContent(HtmlTextWriter __w, Control parameterContainer)
  at ASP.content_kismetvacation_views_shared_site_master.__Render__control1(HtmlTextWriter __w, Control parameterContainer)

System.Web.HttpUnhandledException (0x80004005): Exception of type 'System.Web.HttpUnhandledException' was thrown. ---> System.NullReferenceException: Object reference not set to an instance of an object.
  at ASP.views_reservation_checkout_aspx.__RenderContent2(HtmlTextWriter __w, Control parameterContainer)
  at ASP.content_kismetvacation_views_shared_site_master.__RenderBodyContent(HtmlTextWriter __w, Control parameterContainer)
  at ASP.content_kismetvacation_views_shared_site_master.__Render__control1(HtmlTextWriter __w, Control parameterContainer)

I see your content page in there: *views_reservation_checkout_aspx*
And a view: *content_kismetvacation_views_shared_site_master*

The deepest point shows the web page named ASP.views_reservation_checkout_aspx (ASP/views/reservation/checkout.aspx ?) so you should focus your debugging efforts on the objects and controls in there.

Things to try in that page:

• Set breakpoints in Visual Studio
  • and step through your code line-by-line,
  • along the way inspect instances of things for null.
  • look for a member call (e.g. method or property) on an instance that is null.
• fix and repeat

Answer 2

Yeah, null reference exceptions can be a little tricky. It looks like it's happening inside the "reservation checkout" view itself.